1. Field of the Invention
This invention relates to a disc cartridge, and more particularly to a disc cartridge in which a disc medium such as a hard disc like an optical disc, a photomagnetic disc or a magnetic disc; a floppy disc; or the like is rotatably received.
2. Description of the Prior Art
Conventionally, a tray system or a cartridge system using a casing has been generally employed for protecting a floppy disc, a compact disc, a video disc or the like which is used for a digital-data storing unit, a video unit or the like from damage and dust to ensure its safety during its storage and operation. For this purpose, the casing is provided with a slidable shutter made of metal which is operated to close a pickup inserting hole and/or a drive shaft inserting hole of the casing in nonuse and open them in use.
Such a shutter is slidably reciprocated within a sliding area in a recess formed on a casing so that one side end of a shutter plate may be selectively moved across an opening formed at the casing for serving as a pickup inserting hole for inserting a recording and/or reproducing pickup of a disc cartridge operating unit therethrough into the cartridge, a drive shaft inserting hole, or the like, resulting in operating the opening as desired. Unfortunately, the sliding area defined in the recess is formed to be substantially planar, so that the side end of the shutter plate often strikes against or hitches on a periphery of the opening on a closed side when the shutter is operated to close the opening, because it is substantially impossible to form an edge of the shutter plate free of any bending or deformation. This leads to inconveniences such as incomplete closing of the opening with the shutter, a failure in smooth operation of the shutter, undesirable shaving of the casing by the shutter plate, and the like. Also, the shaving causes dust to be produced from the casing, resulting in deteriorating safety of a disc.
Accordingly, it would be highly desirable to develop a disc cartridge which is capable of ensuring smooth operation of a shutter without adversely affecting operation of the disc cartridge.